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Due to its conjugated structure, 1,4,6,8-tetrakis((E)-2-(thiophen-2-yl)vinyl)azulene (L) has a high potential for nonlinear optics and coloring. This compound was studied electrochemically using cyclic voltammetry, pulse differential voltammetry and rotating disk voltammetry in organic electrolytes. The main processes occurring during oxidation and reduction scans were highlighted and characterized. Density functional theory (DFT) calculations were conducted to assess the chemical reactivity of this compound. UV-Vis studies of L were performed in acetonitrile to establish the optical parameters in this solvent and its complexing power towards heavy metal (HM) ions. Chemically modified electrodes (CMEs) based on L were prepared by electrooxidation of L in organic electrolytes. To evaluate the electrochemical behavior of the CMEs, they were characterized with a ferrocene redox probe. They were also tested for the analysis of synthetic samples of heavy metal ions (HM): Cd(II), Pb(II), Cu(II) and Hg(II) by anodic stripping. Specific responses were obtained for Pb(II) and Cd(II) ions. The preparation conditions have an influence on the electrochemical responses. This study is relevant for the design and further development of advanced materials based on this azulene for the analysis of HMs in water samples. Electrochemical experiments and DFT calculations recommended L as a new ligand for modifying the electrode surface for the analysis of HMs.

The interaction between organic and inorganic nutrients, bacterial communities, and soil fertility has been well documented over time. Conventional agricultural systems heavily utilize both inorganic and organic fertilizers, each exerting distinct effects on soil microbial dynamics and plant growth. The objective of our experiments was to identify the most effective fertilization strategy for improving the biological quality of a microbiologically impoverished and low-productivity soil. To this end, four fertilization strategies were evaluated: (i) organic fertilizers characterized by a high content of organic carbon (Fertil 4-5-7—variant 1); (ii) organic fertilizers with 12% organic nitrogen from proteins (Bio Ostara N—variant 2) (iii) combined inorganic–organic fertilizers (P35 Bio—variant 3) and (iv) mineral (inorganic) fertilizers (BioAktiv—variant V4). This study aimed to assess the short-term effects of fertilizers with varying chemical compositions on the density of cultivable heterotrophic bacteria and their associated dehydrogenase (DH) activity in a petrocalcic chernozem soil containing pedogenic carbonates. Soil sampling was conducted according to a randomized block design, comprising four replicates per treatment (control plus four fertilizer types). The enumeration of cultivable bacteria was performed using Nutrient Agar and A2R Agar media, whereas dehydrogenase activity (DHA) was quantified based on the reduction of 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) to 1,3,5-triphenyl-tetrazolium formazan (TPF) by bacterial dehydrogenase enzymes. Marked differences were observed in both parameters between the plots amended with inorganic fertilizers and those treated with organic fertilizers, as well as among the organic fertilizer treatments of varying composition. The most pronounced increases in both bacterial density and dehydrogenase activity (DHA) were recorded in the plots receiving the fertilizer with a high organic nitrogen content. In this treatment, the maximum bacterial population density reached 6.25 log10 CFU g−1 dry soil after approximately two months (May), followed by a significant decline starting in July. In contrast, DHA exhibited a more rapid response, reaching its peak in April (42.75 µg TPF g−1 soil), indicating an earlier DHA activation of microbial metabolism. This temporal lag between the two parameters suggests that enzymatic activity responded more swiftly to the nutrient inputs than did microbial biomass proliferation. For the other two organic fertilizer variants, bacterial population dynamics were broadly similar, with peak densities recorded in June, ranging from 5.98 log10 CFU g−1 soil (V3) to 6.03 log10 CFU g−1 soil (V1). A comparable trend was observed in DHA: in V3, maximum DHA was attained in June (30 µg TPF g−1 soil), after which it remained relatively stable, whereas in V1, it peaked in June (24.05 µg TPF g−1 soil) and subsequently declined slightly toward the end of the experimental period. Overall, the temporal dynamics of bacterial density and DHA demonstrated a strong dependence on the quality and biodegradability of the organic matter supplied by each fertilizer. Both parameters were consistently lower under inorganic fertilization compared with organic treatments, suggesting that the observed increases in microbial density and activity were primarily mediated by the enhanced availability of organic substrates. The relationship between the density of culturable heterotrophic bacteria and dehydrogenase (DH) activity was strongly positive (r = 0.79), indicating a close functional linkage between bacterial density and oxidative enzyme activity. This connection suggests that the culturable fraction of the heterotrophic microbial community plays a key role in the early stages of organic matter mineralization derived from the applied fertilizers, particularly in the decomposition of easily degradable substrates.

Novel chemically modified electrodes (CMEs) based on azulene were prepared by electrooxidation of guaiazulene derivative 4-((5-isopropyl-3,8-dimethylazulen-1-yl)methylene)-2-phenyloxazol-5(4H)-one (G). G is based on guaiazulene non-alternating aromatic hydrocarbon exhibiting a less symmetrical structure compared to naphthalene skeletal derivative. Therefore, it can be used as a building block for the preparation of novel materials. To evaluate the chemical structure and surface images, the CMEs based on G (G-CMEs) were characterized by ferrocene redox probe, X-ray photon spectroscopy (XPS), and scanning electron microscopy (SEM). They were also tested for the analysis of synthetic samples of heavy metal (HM) ions. The influence of preparation conditions (electric charge and potential) on the properties of these CMEs was examined. This paper highlights the importance of electropolymerization conditions on electrodeposited film surfaces, especially on their analytical properties vs. Cd(II), Pb(II), Cu(II), and Hg(II) investigated ions. This study is relevant for further design and development of advanced materials based on azulenyl-phenyloxazolone for the HM analysis in water. A linear dependence of the peak currents for Pb(II) ion on the concentration in test aqueous solutions was obtained between 10−7 M and 5·10−5 M. The detection limits of 5·10−6 M; 10−7 M; 5·10−6 M; and 10−5 M were estimated for Cd(II), Pb(II), Cu(II), and Hg(II), respectively, for G-CMEs.

The widespread use of Tebuconazole-based fungicides in phytosanitary treatments on a wide range of crops, on the one hand, and the lack of official reports on the amount of fungicide residues in nearby water basins, on the other hand, may lead to uncontrolled and hazardous contamination of water sources used by the resident population, and to serious effects on the environment and public health. Our study explores the acute toxicological risk of this fungicide on various organisms, from bacteria and yeast to fish, using a battery of tests (standardized Toxkit microbiotests and acute semi-static tests). By investigating the interaction between Tebuconazole and bacteria and yeast organisms, we observed that Gram-negative bacteria displayed a strong tolerance for Tebuconazole, while Gram-positive bacteria and yeasts proved to be very sensitive. The fish experiment was conducted on Chelon auratus juveniles exposed to five concentrations of the fungicide Tebustar EW (Tebuconazole, 250 g/L as active substance). After 96 h of exposure, the LC50 for C. auratus was 1.13 mg/L. In the case of the Toxkit microbiotests’ application, the following results were recorded: Spirodela polyrhiza EC50 = 2.204 mg/L (after 72 h exposure), Thamnocephalus platyurus EC50 = 0.115 mg/L (after 24 h), and Daphnia magna EC50 = 2.37 mg/L (after 24–48 h). With the exception of bacteria and yeast, the same response pattern was observed for all non-target species tested; the response range expressed by concentrations causing growth inhibition or mortality was small, ranging between very close values that are quite low, thereby demonstrating the high toxicity of Tebuconazole-based fungicides to the environment.

Chemically modified electrodes (CMEs) based on 2-phenyl-4-((4,6,8-trimethylazulen-1-yl)methylene)oxazol-5(4H)-one (M) were obtained by irreversible electrooxidation of M in millimolar solutions in 0.1 M tetrabutylammonium perchlorate (TBAP) in acetonitrile. These CMEs were characterized by a ferrocene redox probe, electrochemical impedance spectroscopy (EIS), X-ray photon spectroscopy (XPS), and scanning electron microscopy (SEM). The influence of the preparation conditions (charge and potential) was examined. The CMEs were finally used for the analysis of synthetic samples of heavy metal (HM) ions. The paper highlights the importance of potential and electropolymerization charge on the film properties, with accent on recognition of HMs, in order to identify the best conditions for their detection in water. The observed findings are relevant for further design and development of advanced materials based on azulenyl-phenyloxazolone for the analysis of HMs in water.

The present work is connected to the study of electrode conditioning issues for the chemically modified electrodes (CMEs) prepared based on 2,6-bis((E)-2-(thiophen-2-yl)vinyl)-4-(5-isopropyl- 3,8-dimethylazulen-1-yl) pyridine (L). L is irreversibly electrooxidized to polymers leading to L-CMEs. The recognition experiments are the final test of chosen parameters (electropolymerization potential and charge in controlled potential electrolysis (CPE), anodic limit of the overoxidation cycles (OC), number of OC, anodic limit of the equilibration cycles (EC), number of EC, pH of the buffer solutions for HMs accumulation, complexation time, potential and time of reduction). The evidence of film deposition resulted by the change of ferrocene symmetrical signal characteristics on bare electrode in ferrocene solution was the simplest way to prove the formation of L-CMEs. However, finding the best electrode equilibration conditions turned out to be a source of increasing the analytical performance for the CMEs, especially those dedicated to the detection of Pb. The paper underlines the importance of understanding the role of each varied parameter, and of carrying out a systematic study of each possible variable. Optimum conditions for Pb ions analysis, using this new thiophen-vinyl-pyridine-azulene based CMEs, have been established, in order to get the best conditions for its detection in water.

The electrochemical study of 2‐Sulfanylidene‐1,3‐thiazolidin‐4‐one (rhodanine, R) was performed on a glassy carbon working electrode by using three methods: differential pulse voltammetry (DPV), cyclic voltammetry (CV), and linear sweep voltammetry (LSV) at rotating disk electrode voltammetry (RDE). The CV, DPV, and LSV at RDE curves for R were recorded at different concentrations in 0.1 M TBAP/CH3CN. Polymeric films were formed by successive cycling at different potentials and by controlled potential electrolysis. The film formation was proved by recording the CV curves of the chemically modified electrodes (CMEs) in transfer solutions containing ferrocene in 0.1 M TBAP/CH3CN. The obtained CMEs were used for the detection of heavy metal ions. Synthetic samples of heavy metal ions (Cd (II), Pb (II), Cu (II), Hg (II)) of concentrations between 10−7 and 10−5 M were analyzed using CMEs prepared in different conditions. The most intense signal was obtained for Pb(II) ion (estimated detection limit = 10−7 M), which shows that these CMEs can be used for Pb(II) ion detection. The ability of R to form complexes with Pb(II) ion was also tested by UV‐Vis spectrometry. The obtained results showed the formation of Pb(II)R2 as the most stable complex.

Electrochemical and spectral studies of benzylidenerhodanine (BR) were performed in order to develop new sensors for heavy metals (HMs) based on chemically modified electrodes (CMEs). CMEs were obtained by cycling and by controlled potential electrolysis at different potentials and charges. Film formation was demonstrated by recording the CV curves of CMEs in transfer solutions containing ferrocene in 0.1 M TBAP/CH3CN. BR-CMEs were used for the analysis of HMs. Samples of Cd(II), Pb(II), Cu(II), and Hg(II), each possessing concentrations between 10−7 and 10−5 M, were analyzed by using CMEs prepared in different conditions. The most intense signal was obtained for the Pb(II) ion. These BR-CMEs can be used for the analysis of Pb(II) in monitored waters. An electrochemical study was performed at different concentrations of BR in 0.1 M TBAP/CH3CN on a glassy carbon electrode by differential pulse voltammetry, cyclic voltammetry, and rotating disk electrode voltammetry. The complexation ratio in the homogeneous solution has been established by the Mollard method in acetonitrile solutions.

Due to its conjugated structure, 1,4,6,8-tetrakis((E)-2-(thiophen-2-yl)vinyl)azulene (L) has a high potential for nonlinear optics and coloring. This compound was studied electrochemically using cyclic voltammetry, pulse differential voltammetry and rotating disk voltammetry in organic electrolytes. The main processes occurring during oxidation and reduction scans were highlighted and characterized. Density functional theory (DFT) calculations were conducted to assess the chemical reactivity of this compound. UV-Vis studies of L were performed in acetonitrile to establish the optical parameters in this solvent and its complexing power towards heavy metal (HM) ions. Chemically modified electrodes (CMEs) based on L were prepared by electrooxidation of L in organic electrolytes. To evaluate the electrochemical behavior of the CMEs, they were characterized with a ferrocene redox probe. They were also tested for the analysis of synthetic samples of heavy metal ions (HM): Cd(II), Pb(II), Cu(II) and Hg(II) by anodic stripping. Specific responses were obtained for Pb(II) and Cd(II) ions. The preparation conditions have an influence on the electrochemical responses. This study is relevant for the design and further development of advanced materials based on this azulene for the analysis of HMs in water samples. Electrochemical experiments and DFT calculations recommended L as a new ligand for modifying the electrode surface for the analysis of HMs.

Novel chemically modified electrodes (CMEs) based on azulene were prepared by electrooxidation of guaiazulene derivative 4-((5-isopropyl-3,8-dimethylazulen-1-yl)methylene)-2-phenyloxazol-5(4H)-one (G). G is based on guaiazulene non-alternating aromatic hydrocarbon exhibiting a less symmetrical structure compared to naphthalene skeletal derivative. Therefore, it can be used as a building block for the preparation of novel materials. To evaluate the chemical structure and surface images, the CMEs based on G (G-CMEs) were characterized by ferrocene redox probe, X-ray photon spectroscopy (XPS), and scanning electron microscopy (SEM). They were also tested for the analysis of synthetic samples of heavy metal (HM) ions. The influence of preparation conditions (electric charge and potential) on the properties of these CMEs was examined. This paper highlights the importance of electropolymerization conditions on electrodeposited film surfaces, especially on their analytical properties vs. Cd(II), Pb(II), Cu(II), and Hg(II) investigated ions. This study is relevant for further design and development of advanced materials based on azulenyl-phenyloxazolone for the HM analysis in water. A linear dependence of the peak currents for Pb(II) ion on the concentration in test aqueous solutions was obtained between 10[sup.−7] M and 5·10[sup.−5] M. The detection limits of 5·10[sup.−6] M; 10[sup.−7] M; 5·10[sup.−6] M; and 10[sup.−5] M were estimated for Cd(II), Pb(II), Cu(II), and Hg(II), respectively, for G-CMEs.